Since we want to keep the Cygnus Update thread clear of wandering discussions, a separate discussion thread is needed to cover questions I wanted to ask. I'll start the thread off with my question that got deleted.

In the event that there is something very wrong with the AJ-26 engines and Antares is grounded for a long period of time (1-3 years), it may be difficult for SpaceX to pick up the slack. They are geared up to build more F9s than Dragons. So Orbital still has value to add during an Antares stand down by continuing to build Cygnus if they can fly it on another rocket.

I started off by noting that both Cygnus and Orbital's SES-8 satellite are both based on Orbital's STAR bus. Orbital is intimately familiar with the F9 fairing and payload interface, so if Cygnus fits inside the F9 fairing, is Cygnus compatible with F9? How are Cygnus and SES-8 different from a pad/fairing interface point of view?

And I responded:No issue with that, and actually flying on ULA keeps launcher redundancy. If Cygnus goes on F9, and SpaceX has a failure, we have no US cargo capability.

I'm just more familiar with recent SpaceX launces, so I was looking at the SES-8 launch, because of the STAR bus. But Delta II launched OCO-2 built around the LEOStar bus.

So the question stands. If an alternate launcher (ULA or F9) has launched an Orbital Satellite based on the STAR bus, then is the payload interface compatible with Cygnus? What new work would have to be done?

In the financial conference call this morning, the question about outsourcing was passed. You can't read too much in that but it sounds like they aren't ruling it out yet and the topic is sensitive enough that they aren't saying anything about it yet.

So the question stands. If an alternate launcher (ULA or F9) has launched an Orbital Satellite based on the STAR bus, then is the payload interface compatible with Cygnus? What new work would have to be done?

All the analytical integration work.Little if anything mechanical work would need to be done if they use an existing adapter. Fairing access would be some work if needed.

Orb/Cygnus was not really expected to launch again until Q1 2015, and the next one after that was in the Summer of 2015. So it does not appear to me they will miss much with a 6-9 month delay in launches.

SpaceX has about 5 Dragon's planned for 2015, so it is not likely they could squeeze in any more.

A year long delay OTOH, would definitely be a problem. Might have to order another ATV or HTV. Dragon does not do garbage duty anyway.

Orb/Cygnus was not really expected to launch again until Q1 2015, and the next one after that was in the Summer of 2015. So it does not appear to me they will miss much with a 6-9 month delay in launches.

SpaceX has about 5 Dragon's planned for 2015, so it is not likely they could squeeze in any more.

A year long delay OTOH, would definitely be a problem. Might have to order another ATV or HTV. Dragon does not do garbage duty either.

ATV's are now out of production. Not sure about HTV. Unless Dragon production can be accelerated (I think this is the long pole for SpaceX CRS launches) then launching Cygnus on F9 might be an option. Especially if Antares won't fly for a year.

Yes, Atlas V could to it as well - but I think SpaceX has more schedule flexibility with its customers. They also have a CRS contract with NASA, which might give NASA some leverage to make them add a Cygnus launch? (or not)

For the purposes of full non-perishable supply to ISS with the planned Cygnus craft.1) How many Cygnus could be lofted at a time by a Falcon Heavy?2) If close to the number of mission Orbital has planned for ISS in it's downtime would Orbital or Nasa consider placing them in a parking orbit and then sending Cygnus as needed from that orbit to ISS?3) Could a Cygnus remain parked in an orbit for a long time before being used? (batteries etc.)4) What would it take to convince Elon or Orbital to risk this on the Falcon Heavy test flight?

^^^ The fairing for FH isn't any bigger than the fairing for F9. So the FH doesn't buy you anything, can only loft one Cygnus per launch. I think F9 could lift the enhanced Cygnus (assuming it fits) fully loaded. Dragon is always volume, not payload limited and Cygnus doesn't have a trunk.

For the purposes of full non-perishable supply to ISS with the planned Cygnus craft.1) How many Cygnus could be lofted at a time by a Falcon Heavy?2) If close to the number of mission Orbital has planned for ISS in it's downtime would Orbital or Nasa consider placing them in a parking orbit and then sending Cygnus as needed from that orbit to ISS?3) Could a Cygnus remain parked in an orbit for a long time before being used? (batteries etc.)4) What would it take to convince Elon or Orbital to risk this on the Falcon Heavy test flight?

^^^ The fairing for FH isn't any bigger than the fairing for F9. So the FH doesn't buy you anything, can only loft one Cygnus per launch. I think F9 could lift the enhanced Cygnus (assuming it fits) fully loaded. Dragon is always volume, not payload limited and Cygnus doesn't have a trunk.

#1,#2,#4: No need for the Falcon Heavy, the F9 can lift the enhanced Cygnus at full cargo mass with the current PLF.

For the purposes of full non-perishable supply to ISS with the planned Cygnus craft.1) How many Cygnus could be lofted at a time by a Falcon Heavy?2) If close to the number of mission Orbital has planned for ISS in it's downtime would Orbital or Nasa consider placing them in a parking orbit and then sending Cygnus as needed from that orbit to ISS?3) Could a Cygnus remain parked in an orbit for a long time before being used? (batteries etc.)4) What would it take to convince Elon or Orbital to risk this on the Falcon Heavy test flight?

I am hoping the Antares mishap will motivate Orbital to pursue integration of Cygnus on Delta IV, both as a backup strategy for CRS if Antares doesn't return to flight soon, and as a forward-looking strategy to expand the capabilities of Cygnus beyond LEO ISS resupply.

Although technically they may be more capable, from a broader perspective neither Atlas nor Falcon works as well as Delta in the alternate CRS launcher role. With Atlas it's the RD-180 problem; with Falcon it's the lack of CRS launcher diversity (viz. Dragon) problem. I'm not sure which Delta IV M+ variant would be appropriate for launching an Enhanced Cygnus to ISS. Has anyone explored that?

On the forward-looking aspect: Antares was never going to be a launcher that could take a Cygnus beyond LEO, e.g. for cargo resupply of a mission in a lunar DRO. I assume Delta IV Heavy as the launcher for this role. Having already flown at least one LEO Cygnus on a DIV-M would provide some level of risk reduction prior to proceeding with a BLEO Cygnus on DIV-H....

I am hoping the Antares mishap will motivate Orbital to pursue integration of Cygnus on Delta IV, both as a backup strategy for CRS if Antares doesn't return to flight soon, and as a forward-looking strategy to expand the capabilities of Cygnus beyond LEO ISS resupply.

Delta IV is one of the most expensive rockets in the world. Orbital has a fixed price contract. That is not going to happen.

Re alternative LVs for Cygnus, how about Soyuz? Commercially available through a "western" provider (Arianespace from CSG or Baikonur with Starsem), presumably cheaper than Atlas and Delta, payload to LEO and fairing size (with ST fairing) should be sufficient.

Not really a serious suggestion, but seems like a better fit than most of the alternatives.